One-month old Zygophyllum xanthoxylon seedlings were grown under five different Ni concentrations （0, 50, 150, 450 and 900 mg/kg）. Growth parameters, tissues Ni accumulation, soluble protein content, photosynthetic ...One-month old Zygophyllum xanthoxylon seedlings were grown under five different Ni concentrations （0, 50, 150, 450 and 900 mg/kg）. Growth parameters, tissues Ni accumulation, soluble protein content, photosynthetic pigment content, lipid peroxidation, antioxidative enzyme activities, and proline content were studied after one month of Ni exposure. The significant reduction in fresh biomass in the shoot and roots was detected at high Ni concentrations （≥450 mg/kg）, whereas dry biomass was not significantly affected in both organs by any of the Ni doses tested. The Ni contents in the shoots and roots increased in a dose-dependent manner, and Ni contents in roots were higher than that in shoots at all treatments. The high Ni doses elevated soluble protein contents in leaves and roots. No visible symptoms of chlorosis were observed in leaves of plants grown in presence of Ni. Malondialdehyde （MDA） contents significantly increased in leaves and roots at high Ni treatments （≥450 mg/kg）, indicating that Ni induces oxidative stress. Enzyme activities might play a central role in cellular protection against the Ni induced oxidative stress. Proline contents proportionally increased with the elevated Ni concentrations. Zygophyllum xanthoxylon revealed moderate Ni tolerance under tested culture conditions, and could be used as tools for revegetation for erosion control in moderate Ni contaminated sites.展开更多
Aims How seed dispersal distance is related to various factors is a major challenge for seed ecologists.However,there are different answers as to which factor is most important in determining wind dispersal distance.T...Aims How seed dispersal distance is related to various factors is a major challenge for seed ecologists.However,there are different answers as to which factor is most important in determining wind dispersal distance.This study is to quantitatively describe the relationship between various factors and primary wind dispersal distance of winged diaspores.Methods The dispersal distances of five morphologies of winged diaspores in Zygophyllum xanthoxylum(Zygophyllaceae)were measured under controlled conditions in a wind tunnel.The explanatory power of environmental factor(i.e.wind speed),plant trait(i.e.release height)and diaspore attributes(i.e.wing loading(the ratio of diaspore mass to projected area),settlement-velocity,shape index(the variance of diaspore length,width and thickness))to the variation in dispersal distance was assessed by releasing diaspores at varying wind speeds and release heights.Important Findings Wind speed and seed release height were the strongest explanatory factors to dispersal distance,contributing 41.1%and 24.8%(P<0.01)to total variation in dispersal distance,respectively.Wind speed accounted more for relatively light disc-shaped seeds than for relatively heavy spherical seeds.Wing loading,shape index and settlement-velocity explained 9.0%(P<0.01),1.4%(P<0.01)and 0.9%(not significant)of the variation in dispersal distance,respectively.From disc-shaped to four-winged diaspores,relative contributions of wing loading and shape index decreased but contribution of settlementvelocity increased.The relative contributions of various factors to wind seed dispersal distance may change with the change in seed morphology.展开更多
基金supported by the China National Funds for Distinguished Young Scientists (No. 40825001)the Talent Training Program for Young Scientist in West China of Chinese Academy of Sciences
文摘One-month old Zygophyllum xanthoxylon seedlings were grown under five different Ni concentrations （0, 50, 150, 450 and 900 mg/kg）. Growth parameters, tissues Ni accumulation, soluble protein content, photosynthetic pigment content, lipid peroxidation, antioxidative enzyme activities, and proline content were studied after one month of Ni exposure. The significant reduction in fresh biomass in the shoot and roots was detected at high Ni concentrations （≥450 mg/kg）, whereas dry biomass was not significantly affected in both organs by any of the Ni doses tested. The Ni contents in the shoots and roots increased in a dose-dependent manner, and Ni contents in roots were higher than that in shoots at all treatments. The high Ni doses elevated soluble protein contents in leaves and roots. No visible symptoms of chlorosis were observed in leaves of plants grown in presence of Ni. Malondialdehyde （MDA） contents significantly increased in leaves and roots at high Ni treatments （≥450 mg/kg）, indicating that Ni induces oxidative stress. Enzyme activities might play a central role in cellular protection against the Ni induced oxidative stress. Proline contents proportionally increased with the elevated Ni concentrations. Zygophyllum xanthoxylon revealed moderate Ni tolerance under tested culture conditions, and could be used as tools for revegetation for erosion control in moderate Ni contaminated sites.
基金National Natural Science Foundation of China(41271529 and 31200539).
文摘Aims How seed dispersal distance is related to various factors is a major challenge for seed ecologists.However,there are different answers as to which factor is most important in determining wind dispersal distance.This study is to quantitatively describe the relationship between various factors and primary wind dispersal distance of winged diaspores.Methods The dispersal distances of five morphologies of winged diaspores in Zygophyllum xanthoxylum(Zygophyllaceae)were measured under controlled conditions in a wind tunnel.The explanatory power of environmental factor(i.e.wind speed),plant trait(i.e.release height)and diaspore attributes(i.e.wing loading(the ratio of diaspore mass to projected area),settlement-velocity,shape index(the variance of diaspore length,width and thickness))to the variation in dispersal distance was assessed by releasing diaspores at varying wind speeds and release heights.Important Findings Wind speed and seed release height were the strongest explanatory factors to dispersal distance,contributing 41.1%and 24.8%(P<0.01)to total variation in dispersal distance,respectively.Wind speed accounted more for relatively light disc-shaped seeds than for relatively heavy spherical seeds.Wing loading,shape index and settlement-velocity explained 9.0%(P<0.01),1.4%(P<0.01)and 0.9%(not significant)of the variation in dispersal distance,respectively.From disc-shaped to four-winged diaspores,relative contributions of wing loading and shape index decreased but contribution of settlementvelocity increased.The relative contributions of various factors to wind seed dispersal distance may change with the change in seed morphology.
